EP1530191A2 - Plasmaanzeigetafel mit kleinem Abstand und langgestreckten koplanaren Entladungen - Google Patents

Plasmaanzeigetafel mit kleinem Abstand und langgestreckten koplanaren Entladungen Download PDF

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EP1530191A2
EP1530191A2 EP04105049A EP04105049A EP1530191A2 EP 1530191 A2 EP1530191 A2 EP 1530191A2 EP 04105049 A EP04105049 A EP 04105049A EP 04105049 A EP04105049 A EP 04105049A EP 1530191 A2 EP1530191 A2 EP 1530191A2
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Prior art keywords
coplanar
discharge
electrodes
regions
region
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English (en)
French (fr)
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EP1530191A3 (de
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Laurent Tessier
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Thomson Plasma SAS
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Thomson Plasma SAS
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J11/00—Gas-filled discharge tubes with alternating current induction of the discharge, e.g. alternating current plasma display panels [AC-PDP]; Gas-filled discharge tubes without any main electrode inside the vessel; Gas-filled discharge tubes with at least one main electrode outside the vessel
    • H01J11/20—Constructional details
    • H01J11/22—Electrodes, e.g. special shape, material or configuration
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J11/00—Gas-filled discharge tubes with alternating current induction of the discharge, e.g. alternating current plasma display panels [AC-PDP]; Gas-filled discharge tubes without any main electrode inside the vessel; Gas-filled discharge tubes with at least one main electrode outside the vessel
    • H01J11/20—Constructional details
    • H01J11/22—Electrodes, e.g. special shape, material or configuration
    • H01J11/32—Disposition of the electrodes
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/22—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources
    • G09G3/28—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using luminous gas-discharge panels, e.g. plasma panels
    • G09G3/288—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using luminous gas-discharge panels, e.g. plasma panels using AC panels
    • G09G3/291—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using luminous gas-discharge panels, e.g. plasma panels using AC panels controlling the gas discharge to control a cell condition, e.g. by means of specific pulse shapes
    • G09G3/294—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using luminous gas-discharge panels, e.g. plasma panels using AC panels controlling the gas discharge to control a cell condition, e.g. by means of specific pulse shapes for lighting or sustain discharge
    • G09G3/2942—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using luminous gas-discharge panels, e.g. plasma panels using AC panels controlling the gas discharge to control a cell condition, e.g. by means of specific pulse shapes for lighting or sustain discharge with special waveforms to increase luminous efficiency
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J1/00—Details of electrodes, of magnetic control means, of screens, or of the mounting or spacing thereof, common to two or more basic types of discharge tubes or lamps
    • H01J1/54—Screens on or from which an image or pattern is formed, picked-up, converted, or stored; Luminescent coatings on vessels
    • H01J1/62—Luminescent screens; Selection of materials for luminescent coatings on vessels
    • H01J1/72—Luminescent screens; Selection of materials for luminescent coatings on vessels with luminescent material discontinuously arranged, e.g. in dots or lines
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J11/00—Gas-filled discharge tubes with alternating current induction of the discharge, e.g. alternating current plasma display panels [AC-PDP]; Gas-filled discharge tubes without any main electrode inside the vessel; Gas-filled discharge tubes with at least one main electrode outside the vessel
    • H01J11/10—AC-PDPs with at least one main electrode being out of contact with the plasma
    • H01J11/12—AC-PDPs with at least one main electrode being out of contact with the plasma with main electrodes provided on both sides of the discharge space
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J11/00—Gas-filled discharge tubes with alternating current induction of the discharge, e.g. alternating current plasma display panels [AC-PDP]; Gas-filled discharge tubes without any main electrode inside the vessel; Gas-filled discharge tubes with at least one main electrode outside the vessel
    • H01J11/20—Constructional details
    • H01J11/22—Electrodes, e.g. special shape, material or configuration
    • H01J11/24—Sustain electrodes or scan electrodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2211/00—Plasma display panels with alternate current induction of the discharge, e.g. AC-PDPs
    • H01J2211/20—Constructional details
    • H01J2211/22—Electrodes
    • H01J2211/32—Disposition of the electrodes
    • H01J2211/323—Mutual disposition of electrodes

Definitions

  • a plasma display panel of the prior art comprises, as shown in Figures 1A and 1B, a first plate 1, generally provided with at least a first and a second array of coplanar electrodes Y, Y', and a second plate 2 provided with an array of electrodes X, called address electrodes, forming between them a two-dimensional set of elementary discharge regions, filled with a discharge gas, each positioned at the intersection of an address electrode X and a pair of electrodes of the first and the second array of coplanar electrodes.
  • the methods for driving a panel of this kind are suitable for displaying images divided into a succession of frames, in which each frame is itself divided into a succession of subframes in order to generate the various grey levels, where each subframe generally comprises an address phase followed by a sustain phase:
  • the matrix discharges are generally caused only during address phases, or phases other than the sustain phases, such as for example the reset phases.
  • Documents EP 1 294 006 and US 6 295 040 illustrate such image display devices, and also the article entitled " A new method to reduce addressing time in a large AC plasma display panel "in IEEE Transactions on Electron Devices, Vol. 48, No. 6, June 2001, pp. 1082-1096, which describes a plasma display panel structure enabling the duration of the address phases for each subframe to be shortened.
  • the invention relates to a plasma display panel with coplanar electrodes, of a particular type associated here, in contrast, with a drive method in which, during the sustain phases for displaying the subframes, the coplanar discharges are each initiated by matrix discharges.
  • the electrodes of both the first and second array of coplanar electrodes of the plate 1 are generally directed so as to be mutually parallel; each electrode Y of the first array is adjacent to an electrode Y' of the second array, is paired with it and is intended to serve a set of coplanar discharge regions, and vice versa for each electrode Y' of the second array.
  • the arrays of coplanar electrodes are coated with a dielectric layer 3 in order to provide a memory effect, this layer itself being coated with a protective and secondary-electron-emitting layer 4, generally based on magnesia.
  • the adjacent elementary discharge regions are generally bounded by horizontal barrier ribs 5 and/or vertical barrier ribs 6; these barrier ribs generally serve also as spacers between the plates.
  • the address electrodes are generally covered with a layer of dielectric material 7 in order to provide a memory effect; this layer has a uniform thickness in that part of the plate 2 which forms the wall of the discharge region.
  • the address electrode In each discharge region or cell of the display panel, the address electrode therefore crosses two coplanar electrodes; in each of the two corresponding crossing regions, we may define:
  • the "gas height" in each cell of the display panel corresponds to the gap separating the two plates; in the rest of the description, the gas height is approximately constant in each cell, and therefore in particular identical in the case of the two matrix discharge regions of each cell; the gas height in the matrix discharge region corresponds to the gap between the regions Z m and Z mx in this region.
  • An elementary discharge region or cell of the display panel therefore comprises at least two matrix discharge regions extending between the plates and a coplanar discharge region extending over the first plate at the coplanar electrodes and between them.
  • Each set of elementary discharge regions served by one and the same pair of electrodes corresponds in general to a horizontal row of elementary discharge regions, cells or subpixels of the display panel; each set of elementary discharge regions served by one and the same address electrode corresponds in general to a vertical column of elementary discharge regions, cells or subpixels.
  • the walls of the discharge regions are generally partly coated with phosphors sensitive to the ultraviolet radiation from the luminous discharges; adjacent column discharge regions are provided with phosphors that emit different primary colours, so that the combination of these three adjacent elementary regions or subpixels in one and the same row forms a picture element or pixel.
  • the cell shown in Figures 1A and 1B is of rectangular shape (other cell geometries have been disclosed in the prior art); the largest dimension of this cell lies parallel to the address electrodes X, where Ox is the longitudinal axis of symmetry of this cell.
  • the portions of electrodes Y, Y' bounded by the vertical barrier ribs 6 separating the columns have a width L E measured parallel to the Ox axis - this electrode width L E is in this case constant over the entire width of the cell.
  • One object of the invention is to combine a drive method in which the coplanar discharges are each initiated by matrix discharges with a plasma display panel having coplanar electrodes and a structure suitable for obtaining the highest luminous efficiencies with this display method.
  • the subject of the invention is an image display device comprising:
  • each elementary discharge region is generally traversed by two coplanar electrodes, which then form a pair; the invention also covers the case of display panels in which each elementary discharge region is traversed by at least three coplanar electrodes, which then form a group of electrodes.
  • the matrix discharges arise "spontaneously", and initiate, each one, a coplanar discharge;
  • the suitable value of the address electrode potential is preferably constant. This constant value is suitable for obtaining coplanar discharges and for initiating a matrix discharge before each coplanar discharge.
  • the matrix discharges are, on the contrary, caused by a matrix voltage pulse and also initiate, each one, a coplanar discharge.
  • the luminous efficiency of the device according to the invention is improved even more by using coplanar voltage pulses whose rise time corresponds to a rate of voltage variation of between 0.2 V/ns and 1 V/ns.
  • the plasma display panel comprises a first plate, provided with at least two arrays of coplanar electrodes that are coated with a dielectric layer, and a second plate provided with an array of electrodes called address electrodes that are coated with a dielectric layer, forming between them a two-dimensional set of elementary discharge regions corresponding to pixels or subpixels of the images to be displayed, said regions being filled with a discharge gas and each being positioned at the point where an address electrode crosses a pair of electrodes formed by an electrode of each coplanar array, in which each elementary discharge region is subdivided into:
  • each electrode of a coplanar array extends over its width between an edge called the internal edge, facing an electrode of the other coplanar array traversing the same elementary discharge regions, and an edge called the external edge at the boundary of the coplanar discharge regions of these elementary regions.
  • each matrix discharge region is therefore located closer to the external edge than the internal edge of the coplanar electrode with which this matrix discharge region is associated.
  • the geometry of the electrodes and/or the nature of the walls of this elementary region and/or the shape of these walls are designed to localize each matrix discharge region closer to the external edge than the internal edge of the coplanar electrode with which this matrix discharge region is associated.
  • the elementary discharge regions are generally separated by barrier ribs, which also serve as spacers between the plates.
  • the second plate and the sides of the barrier ribs are generally coated with phosphor materials capable of emitting visible light when excited by the ultraviolet radiation emitted by the discharges;
  • the coplanar electrodes are coated with a dielectric layer which itself is generally coated with a protective and secondary-electron-emitting layer;
  • the address electrodes are also coated with a dielectric layer which may be a layer made of the same material as that of the barrier ribs and/or of the phosphor material.
  • the luminous efficiency of the device according to the invention is improved even more by using, in the discharge gas, an Xe concentration of between 3% and 20%.
  • the gap separating the internal edges of the coplanar electrodes of each pair or each group is, in each coplanar discharge region, less than or equal to twice the average gap separating the two plates, this gap corresponding to the average gas height in the display panel.
  • These "internal" edges correspond to the edges that face each other within one and the same discharge region.
  • This gap between the coplanar electrodes of one and the same pair may be substantially greater outside the coplanar discharge regions, especially if these electrodes are provided with indentations placed at the barrier ribs that separate the discharge regions of the display panel.
  • the gap separating the internal edges of the coplanar electrodes of each pair is less than or equal to 200 ⁇ m.
  • the amplitude of the sustain pulses which is necessary for obtaining the coplanar discharges, is advantageously limited, generally to between 100 and 200 V.
  • the dielectric layer covering the address electrodes on the second plate is subdivided into two types of regions:
  • the display panel obtained therefore corresponds to the 2nd embodiment described in detail below. Thanks to the specific nature of the walls of the elementary discharge regions in the dielectric layer covering the address electrodes, it is possible to localize each matrix discharge region closer to the external edge than the internal edge of the coplanar electrode with which it is associated.
  • the panel obtained therefore corresponds to the 3rd embodiment described in detail below.
  • the edge referred to as the lateral edge of each indentation, which faces one or other of the barrier ribs, is separated from these barrier ribs by at least 50 ⁇ m.
  • the average gas height is lower at the rear halves of the coplanar electrodes than at the front halves of these electrodes.
  • the panel obtained therefore corresponds to the 4th embodiment described in detail below. Thanks to this specific geometry of the elementary discharge regions, it is possible to localize each matrix discharge region closer to the external edge than the internal edge of the coplanar electrode with which it is associated.
  • the external edge of the coplanar electrodes limits expansion of the coplanar discharges.
  • Each image frame to be displayed is generally divided into subframes of various durations corresponding to various grey levels.
  • the display of each subframe generally comprises, in succession, a reset phase, in which the elementary discharge regions are reset, an address phase, for the purpose of depositing charges only in the elementary regions to be activated in order to display the image subframe, and a sustain phase, during which a series of sustain pulses is applied over the duration of the subframe, the voltage of the sustain pulses being such as to induce coplanar discharges only in the elementary regions activated beforehand.
  • a voltage pulse called a "matrix" pulse is applied between this cathode and the address electrode traversing this region, which has an amplitude such as to induce a matrix discharge between this cathode and the address electrode serving as anode.
  • each matrix pulse for initiating a coplanar discharge starts just before the start of the sustain pulse that generates this coplanar discharge; preferably, this matrix pulse starts even before the end of the preceding sustain pulse.
  • the potential difference between the coplanar electrodes between two sustain pulses has no intermediate voltage plateau, especially no zero voltage plateau.
  • each coplanar discharge has spontaneous matrix discharges or induced matrix discharges, as soon as each coplanar discharge appears it "straddles" not only the coplanar inter-electrode region but also at least the front half of the coplanar electrode serving as cathode during this discharge, this front half being bounded by the internal edge of this electrode; in this way, each coplanar discharge has, as soon as it appears, a high expansion level, thereby providing a very high luminous efficiency.
  • the electrode area corresponding to the rear electrode half, which is bordered by its external edge is smaller than the electrode area corresponding to the front electrode half, which is bordered by its internal edge.
  • the matrix discharge regions can thus be positioned closer to the external edges than the internal edges of the coplanar electrodes.
  • each coplanar sustain discharge arising between the electrodes of a coplanar pair, one serving as cathode and the other as anode comprises a coplanar ignition phase and a coplanar expansion phase;
  • Figure 2A shows the various ignition and expansion steps of such a coplanar discharge, in a schematic longitudinal section of a cell as described in Figure 1A;
  • Figure 2B shows, as a function of the time T of this discharge, the schematic variation in the intensity of its electric current I (solid curve) and the variation in its spread (dotted curve) between the coplanar electrodes.
  • the discharge ignition voltage obviously depends on the electrical charges stored beforehand on the anode and the cathode in the vicinity of the ignition region, especially during the preceding sustain discharge in which the cathode was an anode, and vice versa; before a discharge, positive charges are therefore stored on the anode and negative charges on the cathode - these stored charges create what is called a memory voltage.
  • the gas ignition voltage corresponds to the sum of this memory voltage and of the voltage applied between the coplanar electrodes, that is to say the sustain voltage.
  • the electron avalanche in the discharge gas between the electrodes then creates a positive space charge that is concentrated around the cathode, to form what is called the cathode sheath.
  • the plasma region called the positive pseudo-column located between the cathode sheath and the anode end of the discharge contains positive and negative charges in approximately identical proportions. This region is therefore current conducting and the electric field therein is low. In this positive pseudo-column region, the electron energy therefore remains low, which favours effective excitation of the discharge gas and consequently the emission of ultraviolet photons.
  • the discharge forms the plasma density is low and the current I is almost zero.
  • the spread of the discharge is very small, this discharge still essentially being confined between the opposed ignition edges of the two coplanar electrodes, as illustrated in the "T a " part of Figure 2-A.
  • the largest part of the electric field in the gas between the anode and the cathode therefore corresponds to the field within the cathode sheath; the impact of the ions, which are accelerated in the intense field of the cathode sheath, on the magnesia-based layer that coats the dielectric layer, results in considerable emission of secondary electrons near the cathode.
  • the density of the conducting plasma between the coplanar conducting elements then greatly increases, in both ion density and electron density, thereby causing the cathode sheath to contract near the cathode and positioning this sheath at the point where the positive charges of the plasma are deposited on the portion of the dielectric surface covering the cathode; on the anode side, the electrons in the plasma, which are much more mobile than the ions, are deposited on that portion of the dielectric surface covering the anode, in order to neutralize, progressively from the front rearwards, the layer of positive "memory" charges stored beforehand.
  • the distribution of the potential along the longitudinal axis Ox on the surface of the dielectric layer covering the cathode is uniform and therefore no transverse electric field for displacing the cathode sheath exists.
  • the positive charge coming from the discharge is therefore deposited and therefore progressively builds up in the ignition region Z a of the cathode, still without there being any displacement of the sheath.
  • the ignition region Z a therefore corresponds to an ion accumulation region at the start of the discharge throughout the period during which the cathode sheath of this discharge is not displaced, that is to say for T ⁇ T Imax .
  • the ion bombardment of the cathode is therefore concentrated on a small area of the magnesia layer covering this cathode and induces strong local sputtering of this layer.
  • a "transverse" field is then created, on the one hand under the effect of these positive charges that have just been deposited on the cathode and, on the other hand, under the combined effect of the negative charges pre-existing on this cathode (for example owing to the preceding discharge) and of the potential applied to this cathode (sustain voltage pulse).
  • this transverse field causes displacement of the cathode sheath further and further away from the ignition region as the ionic charges progressively build up on the dielectric surface portion that covers the cathode; it is this displacement that causes the plasma discharge to expand on the cathode side.
  • the cathode sheath is positioned at the point where the ions in the plasma are deposited, at the boundary of the expansion region. During the coplanar discharge, the cathode sheath moves towards the cathode edge on the opposite side from the ignition edge.
  • the expansion region Z e therefore corresponds to the region swept by the displacement of the discharge cathode sheath, corresponding to the discharge phase between T Imax and T f , the instant discharge spreading stops.
  • the spreading of the discharge over the surface of the dielectric layer, between time T Imax and T f makes it possible to extend the positive pseudo-column region of the discharge, and therefore to increase the electrical energy part of this discharge which is dissipated in order to excite the gas in the cell, and therefore to improve the ultraviolet photon production efficiency of the discharge.
  • the amount of energy dissipated at time T f which corresponds to the electrical current I f at this instant, remains low.
  • One means of improving the luminous efficiency therefore consists in dissipating the maximum amount of energy in the discharge when the latter is at its optimum expansion point, that is to say approaching the time T Imax corresponding to the maximum amount of energy dissipated in the discharge and the time T f when the discharge reaches the spreading limit E f , or else to minimize the spreading E f /E Imax ratio.
  • Figure 3A shows the spreading of the discharge and Figure 3B describes this spread E and the intensity I of the current in this discharge as a function of the time T, in the case in which the display panel is driven according to the principle described in that publication.
  • a zero voltage is applied to the coplanar cathode
  • a positive voltage is applied to the coplanar anode and, in this case, a zero or at least positive constant voltage less than that of the anode is applied to the address electrode.
  • the initial memory charges coming from the preceding discharge in this cell which are deposited on the dielectric layer from one or other of the plates, are negative on the coplanar cathode, positive on the coplanar anode, and generally positive on the address electrode since the latter was connected to a zero potential throughout the end of the sustain pulse of the preceding discharge.
  • the corresponding memory charge is adapted so that, at the end of the discharge, the potential on the surface of the dielectric layer covering the conducting address element is close to the median potential equidistant from the potential applied to the anode and from the potential applied to the coplanar cathode. This therefore results in a non-zero electric field between the address electrode and the coplanar anode in the matrix discharge region located between these two electrodes.
  • the memory charges are therefore not deposited uniformly on the conducting address element.
  • the density of this charge deposition is a maximum in the matrix regions Z mx of the address electrode, these generally being located facing the coplanar ignition regions of each of the coplanar electrodes on the first plate 1, as shown in Figure 4. As this figure illustrates, the density of this deposition is approximately constant within the regions Z mx and progressively decreases on moving away from these regions, away from the ignition edges (only the region Z mx facing the cathode has been indicated in Figure 4).
  • the longitudinal axis Ox of symmetry of the cell also corresponds here to the axis of symmetry of the address electrode; on the surface of the dielectric layer that covers this electrode and is in contact with the gas in the cell, there is therefore, as illustrated in Figure 4, an approximately uniform potential in each of the two matrix discharge regions, and then a potential that decreases along the Ox axis while moving away from the centre of the cell and from these regions.
  • the negative memory charge deposited on the dielectric layer region covering the coplanar cathode Y is itself relatively uniform over at least the first half Z1 of this region, and therefore generates a relatively uniform negative potential (with a maximum in absolute value) over this entire region Z1.
  • Each of the two matrix discharge regions of a cell is defined as a region comprising the entire gas height between the plates and within which the electric field is approximately uniform between the two plates, and is a maximum in order to allow ignition of a matrix discharge specifically in these regions when a matrix pulse is applied.
  • the matrix discharge region located on the cathode side in Figure 4 is bounded by the coplanar region Z m on the coplanar plate and by the matrix region Z mx on the plate bearing the address electrodes. It should be noted here that Z m lies within Z1.
  • the other matrix discharge region, located on the anode side is defined in a similar manner.
  • the abovementioned publication proposes to achieve this breakdown field by superposing, during the sustain phases, a positive matrix voltage pulse on the address electrode, at each positive voltage pulse applied to the anode, as shown in Figure 5, in which Y and Y' act alternately as anode.
  • the frequency of the matrix sustain pulses V x is then twice the frequency of the coplanar sustain pulses V Y , V Y ' that are applied alternately to the two electrodes of each coplanar pair.
  • the coplanar pulse is applied sufficiently rapidly, that is to say in practice less than 1000 ns after the matrix discharge emission maximum according to our determinations, it has been found that the volume charges created by the matrix discharge reduce the gas breakdown field and could on the contrary facilitate initiation of the coplanar discharge between the two coplanar electrodes Y, Y' of the cell.
  • the coplanar discharge then starts far from the internal edge of the cathode, for example at the rear half of the cathode (which is bounded by the external edge) and, as in the previous example, joins the internal edge of the coplanar anode.
  • the coplanar discharge is then much longer at initiation, compared with the example described above.
  • Figure 3-A illustrates at time T Imax , the electrons in the discharge then spread out, as in the case described above, as far as the external edge of the anode so that, when they reach this external edge, the current I max dissipated in the discharge passes through a discharge region that has a spread E Imax greater than that of the previous case illustrated in Figure 2-A.
  • the spread E f /E Imax ratio is therefore minimized, dissipating more energy in the discharge when the latter is extended and thus the luminous efficiency is improved.
  • the increase in discharge spread by this method is limited to about half the distance that separates the internal edge from the external edge of the cathode, so that it is not possible, in practice, to achieve an increase in luminous efficiency of more than 30%.
  • the key for improving the luminous efficiency of plasma display panels lies in inverting the distribution of the energy dissipated during formation of the discharges, so as to dissipate the greatest amount of energy during the high efficiency period of the discharge, for example so that the E f /E Imax ratio is a minimum.
  • the invention proposes to adapt the structure of the discharge regions and the signals applied to the electrodes serving these regions so as to generate the initiating matrix discharges as far away as possible from the internal edges of the coplanar electrodes, and preferably near the external edge of these electrodes (when they act as cathode) and, as soon as the coplanar discharges have been initiated, to make them extend very rapidly over the entire dielectric surface covering them, while still limiting the coplanar sustain voltage.
  • the invention proposes to increase the avalanche gain of the initiating matrix discharge by suitable means, so that the matrix discharge regions lie as far away as possible from the internal edges of the coplanar electrodes, preferably near the external edge of these electrodes.
  • an initiating matrix discharge is forced between the electrode X acting as anode and the electrode Y acting as cathode, between the region Z mx lying above the conducting element X and the region Z m lying opposite the second half of the conducting coplanar element Y acting as cathode, by a local increase in the avalanche gain in this portion of the discharge region, for example according to the embodiments described below.
  • the discharge spreads substantially along the conducting address element X, towards the coplanar anode, owing to the mobility of the electrons in the transverse field created by the potential difference between the positive charges initially stored on the dielectric surface of the plate 2 and the deposition of negative charges coming from the matrix discharge.
  • the avalanche gain is chosen to be greater in the matrix discharge region Z m located here in the coplanar discharge expansion region Z e , the avalanche gain is therefore lower in the coplanar ignition region Z a .
  • the coplanar discharge is therefore initiated naturally, with a slight time shift relative to the initiation matrix discharge and starts only at the time T c after the time T m of the matrix discharge.
  • the two discharges join up and form one and the same highly extended discharge between the internal edge of the anode Y' and a region close to the external edge of the cathode Y.
  • the discharge spreads further, as far as the external edge of the anode Y', and the current maximum I max is reached when the electrons being deposited reach this external edge.
  • the current maximum is therefore reached here when the discharge is already spread between the two external edges of the coplanar electrodes, that is to say when the discharge efficiency is a maximum.
  • the ratio of the spreads E f /E Imax is thus very considerably minimized and the luminous efficiency is improved by more than 60%, proportionally greater than in the case of the prior art.
  • This geometrical definition means that the electrode area corresponding to the rear electrode half that is bordered by its external edge is smaller than the electrode area corresponding to the front electrode half that is bordered by its internal edge.
  • a positive matrix voltage pulse is applied, in each cell and just before each sustain pulse, between the address electrode and the coplanar electrode serving as cathode.
  • a positive matrix voltage pulse is applied, in each cell and just before each sustain pulse, between the address electrode and the coplanar electrode serving as cathode.
  • the amplitude of the matrix pulses is between about 50 V and 100 V.
  • each coplanar discharge is accompanied by a very short matrix discharge which, thanks to the particular structure of the cells, allows the luminous efficiency to be very greatly increased.
  • the dielectric layer 7 covering the address electrodes on the plate 2 is subdivided, in each row of cells, into two types of regions:
  • This length is preferably greater than 50 ⁇ m and the dielectric permittivity of these regions is preferably, and on average, more than three times the dielectric permittivity of the low-permittivity regions.
  • the thickness of the dielectric layer 7 is generally between 5 and 20 ⁇ m.
  • These regions 7a of high dielectric permittivity may be continuous, extending over the entire width of the display panel, or discontinuous, being located only in the cells of the display panel.
  • the barrier ribs separating the columns are subdivided into two types of regions:
  • these high-permittivity regions extend over the entire height of the barrier ribs.
  • the regions of high dielectric permittivity of the dielectric layer 7 are replaced with regions whose surface in contact with the discharge gas has a high photoemissive efficiency, that is to say a surface capable of emitting secondary electrons when it is excited by photons.
  • Figure 9-A shows the measured equipotential electric field lines in the cross section AA' of Figure 8A in a portion of the elementary discharge region which is located in the front half of the coplanar electrode Y and is not a region of high dielectric permittivity.
  • the electric field between the address electrode X and the coplanar electrode Y acting as cathode remains low in the gas space identified as E in the figure, which is close to the top of the cell-separating barrier rib, and does not allow a matrix discharge to be initiated in this space, either during a sustain pulse or between these pulses.
  • Figure 9-B shows the potential lines in the cross section BB' of Figure 8A lying in a portion of the discharge region which is located in the rear half of the coplanar electrode Y and has a region of high dielectric permittivity.
  • the electric field between the between the address electrode X and the coplanar electrode Y acting as cathode in the gas space identified by E' in the figure is much higher than previously, since the region of high dielectric permittivity takes the potential of the address electrode X back to close to the coplanar electrode Y.
  • the discharge gain is increased in these regions by the creation, over the height of gas between the plates, and therefore along the matrix discharge path, of photoelectrons representing as many additional primary charges, generally created from photons emitted by the post discharge of the previous sustain pulse or from photons emitted from the onset of avalanche of the current discharge.
  • the photons are not converted into additional photoelectrons and the discharge gain is smaller.
  • these indentations provide, in the outline of each coplanar electrode, edges called lateral edges that face the walls of the column-separating barrier ribs.
  • the distance d between these lateral edges and these walls is at least 50 ⁇ m.
  • the dielectric layer 7 that coats the address electrodes has a high dielectric permittivity, preferably equal to 30 or higher.
  • Figure 11-A shows the potential lines in the cross section AA' of Figure 10A, for a portion of the elementary discharge region in which the electrode Y acting as cathode has, between opposed lateral edges of one and the same indentation, a non-zero width that is smaller by an amount 2xd than the width W c of the cell, so that, in the space identified by E close to the column-separating barrier, there is no coplanar electrode Y.
  • the electric field in this space identified by E is low so that a matrix discharge will not be initiated in this region, that is to say between 0 and L E /2.
  • Figure 11-B shows the potential lines in the cross section BB' of Figure 10A, for a portion of the discharge region in which the electrode Y acting as cathode does not have an indentation, that is to say in the rear half of the coplanar electrode.
  • the electric field between the address electrode X and the conducting coplanar element Y acting as cathode is much higher than previously, especially in the space E' close to the column-separating barrier rib because of the presence of the electrode Y in this space.
  • the average gas height, in each elementary discharge region is smaller at the rear halves of the coplanar electrodes than at the front halves of these electrodes.
  • Figure 12 illustrates an example of this embodiment:
  • D m ⁇ D c Preferably, D c > 100 ⁇ m and 40 ⁇ m ⁇ D m ⁇ 80 ⁇ m.
  • the reduction in the gap between the coplanar electrodes and the address electrodes in certain regions of the cells is accompanied, for fabrication process reasons, by a reduction in the gap between the side walls of the cells constituting the barrier ribs of the discharge region.
  • FIGS 13A to 13D show very schematically the various types of coplanar sustain discharges that it is possible to obtain with the various types of coplanar display panels, the vertical lines representing schematically the equipotential lines between the coplanar electrodes in these discharges:
  • a much lower electric field is obtained within the coplanar discharges than in the embodiments 1 to 4 described above.
  • One of the means of obtaining this region of low electric field Z w is to use electrode elements of variable length in the interval [0, x bc ] (for the sake of consistency with the terms described above, the term "length” denotes the dimension measured perpendicular to the Ox axis).
  • the invention also applies to other image display devices provided with plasma display panels having coplanar electrodes, provided that they do not depart from the scope of the claims appended hereto.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Plasma & Fusion (AREA)
  • Chemical & Material Sciences (AREA)
  • Materials Engineering (AREA)
  • Power Engineering (AREA)
  • Computer Hardware Design (AREA)
  • General Physics & Mathematics (AREA)
  • Theoretical Computer Science (AREA)
  • Gas-Filled Discharge Tubes (AREA)
  • Control Of Indicators Other Than Cathode Ray Tubes (AREA)
  • Control Of Gas Discharge Display Tubes (AREA)
EP04105049A 2003-11-07 2004-10-14 Plasmaanzeigetafel mit kleinem Abstand und langgestreckten koplanaren Entladungen Withdrawn EP1530191A3 (de)

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FR0350814 2003-11-07
FR0350814 2003-11-07

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WO2007043131A1 (ja) * 2005-10-03 2007-04-19 Fujitsu Hitachi Plasma Display Limited プラズマディスプレイパネル
CN116399428B (zh) * 2023-04-10 2025-09-12 浙江大学 多兴趣区域的非接触式公路荷载识别方法

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KR20050022071A (ko) * 2003-08-26 2005-03-07 삼성에스디아이 주식회사 플라즈마 디스플레이 패널

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KR101103759B1 (ko) 2012-01-12
EP1530191A3 (de) 2008-02-27
KR20050044287A (ko) 2005-05-12
TWI358072B (en) 2012-02-11
US7768475B2 (en) 2010-08-03
TW200516631A (en) 2005-05-16
JP4792217B2 (ja) 2011-10-12
JP2005142161A (ja) 2005-06-02
CN1614735B (zh) 2010-04-28
CN1614735A (zh) 2005-05-11
US20060092101A1 (en) 2006-05-04

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